leetcode 13. Roman to Integer

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本文介绍了一种将罗马数字转换为整数的算法实现，通过解析罗马数字的构成规则，利用C++语言实现了该转换过程。输入范围保证在1到3999之间。

Given a roman numeral, convert it to an integer.

Input is guaranteed to be within the range from 1 to 3999.

解：罗马数字的规则可以搜搜

class Solution {
public:
    int romanToInt(string s) {
        int roman[24] = {};
        roman['I' - 'A'] = 1;
        roman['V' - 'A'] = 5;
        roman['X' - 'A'] = 10;
        roman['L' - 'A'] = 50;
        roman['C' - 'A'] = 100;
        roman['D' - 'A'] = 500;
        roman['M' - 'A'] = 1000;
        int sum = roman[s[s.length() - 1] - 'A'];
        for (int i = s.length() - 2; i >= 0; --i) {
          if (roman[s[i] - 'A'] < roman[s[i + 1] - 'A'])
              sum -= roman[s[i] - 'A'];
          else
              sum += roman[s[i] - 'A'];
        }
        return sum;
    }
};